System of control



A. D. WEBST'ER.

SYSTEM OF CONTROL.

APPLICATION FILED MAY 14, I921.

Patented Dec. 12, 1922'.

Patented Dec. 12, 1922.

UNITED STATES PATENT OFFICE.

ALFRED D. WEBSTER, OF WILKINSBURG, PENNSYLVANIA, ASSIGNOR TO WESTING- HOUSE ELECTRIC & MANUFACTURING COMPANY, A CORPORATION OF PENNSYL- VANIA.

SYSTEM OF CONTROL.

Application filed May 14, 1921. Serial No. 469,422.

To all whom it may concern:

Be itknown that I, ALFRED D. Vncsrnn, a citizen of the United States, and a resident of lVilkinsburg, in the county of Alic gheny and State of Pennsylvania, have invented a new and useful Improvement in Systems of Control, of which the following is a specification.

My invention relates to control systems and it has particular relation to the protection of control systems from excessive overload conditions.

The object of my invention is to provide means for protecting a plurality of motors from an excessive overload throughout the acceleration and normal operation of the motors.

More fully stated, the object of my invention is to provide a relay for governing the operation of a circuit-breaker that will be responsive to overload conditions during the period the motors are operating in series relation and also during their operation in parallel relation.

Heretot'ore, the overload relay governing I the operation of a circuit-breaker of a control system has been set for opening upon the current becoming excessive, when the motors were connected in parallel relation only, and, consequently, the relay afforded inadequate protection when the motors were operating in series relation, as the normal current that was traversing the system was approximately one-half of that which was employed during the period when the motors were in parallel relation.

Briefly speaking, my invention consists in providing a relay having a plurality of actuating coils for governing the operation of a line switch or circuit-breaker connecting one of the coils of the relay in series relation with a plurality of motors that are governed by the control system and having the energization of the other coil governed by one of the series-parallel contactors.

For a. better understanding of my invention, reference may be made to the accompanying drawing; I

Figure 1 of which is a. schematic view of a control system embodying my invention;

Fig. 2 is a. sequence chart showing the order of closure of the switches or contactors employed in the control system illus trated. in Fig. 1

Fig. 3 is a diagrammatic view of a portion of the auxiliary circuits governing the control system shown in Fig. 1; and

Fig. 4 is a. modified form of the control system shown in Fig. 1.

Referring to Fig. 1 of the drawing, a plu rality of motors 1 and 2 having armatures 3 and 4, respectively, and series field-magnet windings 5 and (3, respectively, are energized from a trolley 7 through the trolleypole 8 upon closure of the line switch or circuit-breaker 9. A starting resistor 11 is employed to govern the energization of the motors 1 and 2, and portions thereof may be shunted by means of accelerating contactors 12. 13 and 14.

The motors 1 and 2 may be connected in series relation by means ofseries contactor 15 and they may be connected in parallel relation by means of the parallel contactors 16 and 17. A. reversing drum 18 is employed for reversing the relation of the series fieldmagnet windings 5 and 6 to the armatures 3 and 4:, respectively. of the corresponding motors 1 and 2. A series coil 20, forming part of an overload relay or trip 19, is positioned between the trolley 8 and the circuitbreaker 9. The relay 19 is provided with a second actuating coil 28, as hereinafter more fully set forth.

Referring to Fig. 3 of the drawing, a master controller 21 is employed to govern the circuit-breaker 9 and the series, parallel and accelerating contactors 12 to 17, inclusive. For the sake of clearness, only so much of the auxiliary circuits are shown as are necessary to illustrate my invention.

The controller 21 has an ofl' position, a

low-speed series position 0. a full-speed series position 7) and a toll-speed parallel position 0. lVhen the master controller 21 is actuated to position a, a circuit is established from trolley 7 through contact terminals 22 and 23 of the master controller 21., which are bridged by contact segment 24, and auxiliary or control resistor 25 to ground.

The circuit-breaker or line switch 9 is energized by a circuit that extends from a tap point 26 of the control resistor 25 through the lower contact member of the overload relay 19 and the actuating coil of the circuit-breaker 9 to ground.

As the actuatingcoil 20 of the overload relay 19 carries only approximately onehalf the current When the motors 1 and 2 are operating in series relation that it car ries when the motors l and 2 are o erating in parallel relation, it would take an injuriously high overload for the actuating coil 20 to open the relay 19. However when the series contactor 15 assunies its closed position, a circuit comprising the actuating coil 28 of the relay 1 is established by auxiliary contact member or interloclr 30 that is actuated by the contactor 15. This circuit extends from the tap-point 26 of the control resistor 25 through the actuating coil 28 of the relay 19 and the auxiliary contact member 30 of the series contact-or 15 to ground.

The terminal connections and designs of the actuating coils 20 and 28 are such that the magnetic fields established. by the COllS are lay smaller overload than it only the actuating coil 20 were energized. As soon as the series contactor 15 opens. the circuit conipris inp; the actuating: coi. is brolsien. and the overload relay 19 must be operated solely by the series coil 20 upon the occurrence of an overload upon theinotors l and when they are operated in parallel relation.

A. holding circuit for maintaining the relay 19 in its open position after it has been. actuated thereto by the occurrence of an exressive overload is provided from the tappoint 26 of the auxiliary control. resistor 25 through the actuating: coil 28 ot the relay 19 and the auxiliary contact member of c-.unulative Wherefore the overload. re-

' the series contactor 15 to ground.

The terminal connections and desig i'is ot the actuating coils 20 and such that the magne ic fields established by the coils are cumuh Whereforethe overload lay 19 operates upon the occurrence of a smaller overload than ii? only the actuat g; coil 520 "were energized. As soon as the series contractor l5 opens the circuit coinprisin the actu. ing coil 9.8 is broln. and the ovenload rela 19 must be operated solely by the series coil 20 upon the occurrence of an. over load upon the motors 1 and 2, when they are operated in parallel relation.

A holding circuit for maintaining the relay 19 in its open position after it has been a tuater thereto by the occurrence of an em cess'ye overload is provided. from the tap po nt 26 of the auxiliary control resistor through the actuating coil 28 of the relay l9 and the auxiliary contact member 29, which forms part of the relay 19, to ground. lhe relay 19 will thus return to its closed position only after the roaster controller 21 has been actuated to its oil position.

Referring to Fig. 4 of the drawing. like elements have been'given like reference Chill acters. However, only two accelerating con- ].9 operates upon the occurrence of tactors 31 and are employed for shunting the starting resistor 11, which located betiveen the'trolley 7 the meters 1 and The actuating coils 20 and 28 of the relay 19 are so arranged that their magnetic fields will oppose one another and the energiaation oil the actuating coil 28 governed by parallelronnectino' contactor 16. The ac tuating coil oi the clay 19 is designed to open the relay 19 when the current is es; cessive in the meters 1 and 2 during the period when tley are operating; in series relation.

tiitlll the motors l and 2 are connected in parallel relation. by means of contactcrs l6 (l 17, the meters 1 and are energized circuit from the trolley 7 t ting; coil 20 contact .-.lQl11l)8lS .lrer 9 starting lGSlStOl or the 011- ll Where the circuit divides one branci including:

motor 1 and switch 1''. the other branch including switch 16 and motor 2 whence a coinn'ion ci is completed to ground. An auxiliary circuit continued from the resistor ll, through. the actuating coil 28 of the relay 1.9 and interlock 16in to ground. its the ergization of the motors 1 and is further increased by the closing. oi"- the contactors 31 and after the motors have been connected in parallel relation the errrization or? the actuating coil 28 will be further increase l. making it responsive to the accelcrating: changes of the control tern. The field b ished by the ener ization ot the actuating coil 28 of the relay 1 is adapted to oppose magnetic field cstaolished by the ctuating coil 20 of the relay l9 thereby raising the current setting at which the overload relay will open upon the occurrence of or cad conditions'dun parallel on -.ation the niaotors as (Will .Vlill series operation thereof.

.1 rom the above description. it is apparent iiat l. e iplo ed a sinale relay which \Tlll adeouate c a motor-control sysern durinq both the period in which. the notors are ope ting; in parallel relation the starting period when the motors are operating in series relation. h are shown my invention in two 6331113. it is to be understood that I es,

er modifications may be made in the arran ement cit circuits an apparatus emlOO chines, of

er 'ng the operation of said switch, one of :oi Lug energized durin the machines and the other of is heing energized only during the parlor Jain machines are in a predetermined relation.

a control systen'i, the combination with a plurality or dynamo-electric macitch for connecting said marl 'nes an external circuit, means compris ir of contactors for varying the a pluralit voltage of said machines, and means com pris a relay having a plurality of actuating coils for governing said SWlttli,

the energization of one oi'said coils being governed by the position of one of said contactors.

3. in a control system, the combination with a 1.. fty oi motors, means comprisinga plurality of contactors for connecting s i motors in difl'erent relations one to another, means for energizing said motors and means comprising a relay hav" g a plurality of actuating coils for governing said ener means, one of said coils being in series relation with one of said motors and the other of said coils being enei ir zed during the n 'iod one of said cont; ctors occupics prei'l tern lined position.

4%. In a i-ontrol system, the combination with a plurality of motors, of a circiiiitlurealzer, a contactor for connecting said motors in series relation, a plurality of contactors for connecting Said motors in parallel relation and a relay having plurality 0t actuating coils for governing the operation of said circuit-breaker, one ot said coils being in series relation with said motors and the energization of the other coil being governed by the position oi"? said. series wontactor.

in a control system, the combination with a plurality of dynamoelectric machines, of means for energizing said machines, means for varying the cnergization of said machines. and means comprising a relay having a plurality of actuating coils or governing said energizing means, one of ,'d coils being; energized during the energization of said machines and the other of said coils being energized only while said machines are in a predetermined relation.

6. In a control system, the combination with plurality of dynamo-electric machines, ot a switch for connecting said machines to an external circuit, means for connecting said machines in lifierent relations one to another and means comprising a relay having a plurality oi actuating coils for governing said switch, said coils being so energized that their attractive forces are cumulative while said machines are connected in one relation.

In a control system, the combination a 'h a plura ity of dynamo-electric machines and si tor energizing said machines, oi relay for governing said switch, relay lmving a plura rty of actuating coils, one or aid coils being connected perin ies relation with one of said am re other of said coils being it upon said machines being conprcdetermincd relation one to an- I the energization of said second coil n aining said relay in its open position the occurrence of an electrical overload upon said machine.

8. in a control system, the combination with a plurality of dynamo-electric machines and a switch for energizing said mahines, of a relay having a plurality of poitions g said switch, said relay .501 govern having a plurality of actuating coils, one of said coils being energized only during predetermined cond "ons and after said. relay has been actuated from its normal po sition.

9. In a control system, the combination with a plurality of dynamo-electric machines and a switch for energizing said machines, ot' means comprising a controller for connecting sain machines in different relations, line switch governed by said controller, a re ay having a plurality of positions tor governing said switch, said relay having plurality of acti'iating coils, one of said coils being energized only during predetermined conditions and after said. relay has been actuated from its normal position, and means for preventing said relay from returning to its normal position until after said controller has been returned to its normal position.

10. In a control system, the combination with a plurality of motors, of means comprising a plurality of contactors for connecting said motors different relations, a con .roller having a plurality of positions for governing; said contactors and means comprising a relay having a plurality of actuating coils for governing the energization of said motors, one of said coils being energized only upon one of said contactors occupying a predetermined position, and means for preventing said motors from being rte-energized prior to said controller being returned to its off position.

In testimony whereof, I have hereunto subscribed my name this 10th day of May, 1921.

ALFRED D. VEBSTER. 

